Carbon isotopes and lignin phenols for tracing the floods during the past 70 years in the middle reach of the Changjiang River

The Lake Tian E Zhou(TEZ,an oxbow lake)was formed during the rerouting of the Changjiang River in 1972,with strong influences from the main river channel and flood events.Herein,a sediment core was collected from the Lake TEZ for the measurements of carbon isotopes and biomarkers,including stable carbon isotopes(δ13C),radiocarbon composition(?14C),and lignin phenols,as well as lead-210 to reconstruct recent heavy flood events over the past 70 years.At the 24–26 cm interval,the sediment contained the highest OC%,TN%,and lignin phenols content,as well as significantly depleted 13C but enriched 14C,corresponding to the extreme flood event in 1998.In addition,statistics from t-test showed that lignin phenols normalized to OC(Λ8),the concentration of 3,5-dihydroxy benzoic acid(3,5-BD),and the ratio of p-hydroxy benzophenone to total hydroxyl phenols(PHB/HP)were all significantly different between the layers containing flood deposits and the layers deposited under normal non-flood conditions(p<0.05).These results indicate that the later three parameters are highly related to flood events and can be used as compelling proxies,along with sediment chronology,for hydrological changes and storm/flood events in the river basin and coastal marine environments.

Source and composition of sedimentary organic matter in the head of Three Gorges Reservoir: a multiproxy approach using δ^(13)C,lignin phenols, and lipid biomarker analyses

A multiproxy approach including bulk organic carbon, δ^(13) C, lignin phenols, and lipid biomarker analyses were applied to characterize the source and composition of sedimentary organic matter in the head part of Three Gorges Reservoir. OM consisted of both natural(autochthonous and allochthonous) and anthropogenic inputs.The natural OM included input from vascular plants,especially non-woody angiosperms. The allochthonous input included plankton and microbial production, likely due to localized eutrophication. Anthropogenic inputs likely derived from petroleum input and/or urban activities.Other anthropogenic inputs were untreated sewage waste.These influences were concluded to be regionally specific point sources of pollution based on relative distributions and on the fact that molecular characteristics of sedimentary OM were not distributed smoothly along a gradient.

Lignin depolymerization for phenolic monomers production by sustainable processes

Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove the major hemicelluloses content in the solid feedstocks. Afterward, two sulfur-free pulping processes(soda and organosolv) were applied to extract the largest fraction of lignin. The extracted lignin contained in the liquors was isolated using selective precipitation methods to design a tailor-made technique for obtaining high-purity lignin(in all cases more 90% of purity was reached). Soda process allowed the extraction of more lignin(around 40%–47%) than organosolv process(lower than 20%) regardless of the lignocellulosic source employed.Once the different lignin samples were isolated and characterized, they were depolymerized for the obtaining of small phenolic compounds. Three main streams were produced after the reaction: phenolic enriched oil, residual lignin and coke. After the purification of these fractions, their quantifications and characterization were conducted.The most abundant product of the reaction was residual lignin generated by the undesirable repolymerization of the initial lignin with yields around 30%–45%. The yield of the stream enriched in phenolic oil was higher than 20%. Coke, the lowest added-value product, presented a yield lower than 12% in all the cases. Lignin from organosolv presented higher phenolic oil yields, mainly due to their lower molecular size. This parameter was, thus, considered a key factor to obtain higher yields.

Soybean Seed Phenol, Lignin, and Isoflavones and Sugars Composition Altered by Foliar Boron Application in Soybean under Water Stress

Previous research showed that foliar boron (B) application at flowering or seed-fill growth stages altered seed protein, oil, and fatty acids. The objective of this research was to investigate the effects of foliar B fertilizer on seed phenolics (phenol, lignin, and isoflavones) and sugars concentrations. A repeated greenhouse experiment was conducted on soybean [(Glycine max(L.) Merr.)] under watered and water-stressed conditions. Soybean plants were divided into different sets, and each set was subjected to one of the following treatments: W = plants were watered with no foliar B;WB = plants were watered and received foliar B;WS = plants were water-stressed with no foliar B;WSB = plants were waterstressed and received foliar B. Foliar B was applied at rate of 0.45 kg/ha twice at flowering and twice at seed-fill stages. The results showed that total phenol and lignin concentrations were higher in seed collected from water-stressed plants compared with those collected from watered plants whether B was applied or not. The higher total phenol and lignin concentration in seed collected of water-stressed plants may be due to B-deficiency in plant tissues. Application of B resulted in higher concentrations of total seed B and isoflavones under watered and water-stressed plants. Higher cell wall B was higher in water-stressed plants than in watered plants, having an opposite trend to total B. Application of B resulted in higher seed sucrose in watered and water-stressed plants, but raffinose and stachyose were significantly higher under water-stressed plants. The research demonstrated that foliar B fertilizer altered seed phenol, lignin, isoflavones, and sugars, suggesting that B involved in phenolics and sugar metabolism. The higher cell wall B in waterstressed plants than in watered plants supports previous research that B has mainly a structural role. The higher sucrose resulting from foliar B in watered plants is desirable as sucrose contributes to seed quality. The increase of raffinose and stachyose concentrations in seed of water-stressed plants is undesirable as raffinose, and especially stachyose may be involved in water stress/drought tolerance. The current knowledge would help soybean breeders select for higher phenolic compounds and desirable sugars for higher seed qualities under drought conditions.

Reinforcement of Lignin-Based Phenol-Formaldehyde Adhesive with Nano-Crystalline Cellulose (NCC): Curing Behavior and Bonding Property of Plywood

The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 and 20&degC/min) and the bonding property was evaluated by the wet shear strength and wood failure of two-ply plywood panels after soaking in water (48 hours at room temperature and followed by 1-hour boiling). The test results indicated that the NCC content had little influence on the peak temperature, activation energy and the total heat of reaction of LPF resin at 5 and 10&degC/min. But at 20&degC/min, LPF0.00% (LPF resin without NCC) showed the highest total heat of reaction, while LPF0.25% (LPF resin containing 0.25% NCC content) and LPF0.50% (LPF resin containing 0.50% NCC content) gave the lowest value. The wet shear strength was affected by the NCC content to a certain extent. With regard to the results of one-way analysis of variance, the bonding quality could be improved by NCC and the optimum NCC content ranged from 0.25% to 0.50%. The wood failure was also affected by the NCC content, but the trend with respect to NCC content was not clear.

Soybean Seed Phenol, Lignin, and Isoflavones Partitioning as Affected by Seed Node Position and Genotype Differences

Factors controlling the production and partitioning of seed phenolics within soybean are not understood. Understanding these factors may justify selection for higher levels of seed phenolics because of their beneficial impact on human health and soybean defense mechanism against diseases. The objective of this research was to investigate the partitioning of seed phenolics (phenol, lignin, and isoflavones) along the main stem of soybean genotypes. A repeated green- house experiment was conducted on different soybean genotypes of different maturity and different stem archi-tecture (determinate and indeterminate). Genotypes were DT 97-4290, maturity group (MG) IV;Stressland, MG IV;Hutcheson, MG V;and Tracy-M, MG VI. Seed were harvested from top and bottom nodes at seed-fill stage (R6) and harvest ma- turity stage (R8). At R6, seed phenolic compounds (phenol, lignin, and isoflavones daidzein, genistein, and glycitein) were greater in the bottom seed than the top seed. This trend was observed in DT 97-4290, Tracy-M, and Hutcheson, but not in Stressland. Also, this trend was more obvious with daidzein and genistein isoflavones than glycitein. The maximum phenolic compounds were recorded at R8. The higher phenolic compounds concentration in bottom seed than in top seed was accompanied by higher cell wall boron (B) percentage and lower total B in bottom seed. The current research demonstrated that phenolic compounds partitioned differently between the top and bottom seed nodes. This trend cannot be generalized in soybean genotypes unless enough germplasm is tested. The partitioning of higher phenolic compounds concentration along the main stem would allow for single seed selection in the breeding program for higher levels of phenolic compounds and for accurate measurements of seed phenolics in breeding lines. The associa- tion of B trend with phenolic compound trend may suggest B involvement in phenolic metabolism, and support the structural role of B. Breeding for higher levels of phenolics, especially isoflavones, would benefit human health, pro- vide higher nutritional value of soy meal, and increase plant disease resistance.

三聚氰胺改性对木质素酚醛树脂胶合性能的影响

【目的】通过三聚氰胺对木质素酚醛树脂(LPF)改性,提高LPF的胶合性能,降低固化温度,为人造板的绿色生产和节能降耗提供新思路。【方法】对比三聚氰胺与(苯酚+木质素)、三聚氰胺/(苯酚+木质素)与甲醛不同摩尔比对三聚氰胺改性木质素酚醛树脂(MLPF)的性能影响,得到MLPF的最佳合成条件。并与相同酚醛比和木质素取代率的酚醛树脂(PF)和LPF进行性能对比,利用FTIR和DSC对PF、LPF和MLPF的结构和固化温度进行比较分析。【结果】当三聚氰胺与(苯酚+木质素)的摩尔比为4∶6、三聚氰胺/(苯酚+木质素)与甲醛的摩尔比为1∶2时,MLPF的凝胶时间最短,为318.62 s,所压制的MLPF胶合板干、湿胶合强度为2.04和1.43 MPa,甲醛释放量为0.088 mg/m^(3),且与PF和LPF胶合板相比MLPF的胶合强度更高,满足GB/T14732—2017和GB/T 9846—2015国家标准性能要求。FTIR结果显示,相较于PF和LPF,MLPF在3 327 cm^(-1)和3 214 cm^(-1)处拥有属于-OH和-N-H的双峰,在1 079 cm^(-1)和1 036 cm^(-1)处出现的N-C-N特征峰以及在809 cm^(-1)处属于三嗪环面外震动的吸收峰,都证明了三聚氰胺经过羟甲基化并参与到MLPF的合成中。DSC结果显示,经过三聚氰胺改性后的MLPF放热峰值温度出现在140℃,其固化温度相较于LPF和PF分别降低了17.16%和22.22%。【结论】三聚氰胺的加入使得MLPF的凝胶时间更短,固化温度更低,MLPF胶合板的性能相较于LPF无论是胶合强度还是耐水性均有明显提升。

矩阵理论在改性胶粘剂制备与设计中的应用研究

基于矩阵理论对酚醛树脂胶粘剂中苯酚进行了木质素替代和酚化改性处理,研究了不同木质素对苯酚替代料对胶粘材料物性的影响,考察了酚化木质素基酚醛树脂胶粘剂的物理性能并与标准GB/T14732、GB/T 9846.3进行了对照。结果表明,酚化处理后木质素酚醛树脂胶粘剂的-COOH含量和脂肪族羟基含量相对有所减小,而总酚羟基含量和活性点含量有所增加。与GB/T 14732-2017标准要求进行对比,不同KL、F1、F2和F3替代率的木质素酚醛树脂胶粘剂的pH值、固含量、游离酚含量和胶接强度满足标准要求,而游离醛含量和甲醛释放量不满足标准要求;F3替代率为15%~35%的胶粘剂的游离醛含量和甲醛释放量不满足标准要求,F3替代率为5%的胶粘剂的游离醛含量和甲醛释放量满足标准要求。PF、PKLPF、PF1-LPF、PF2-LPF和PF3-LPF的游离醛含量、甲醛释放量和胶接强度满足标准要求。

微生物关键种影响植物残体还田条件下木质素酚浓度——基于30年长期有机培肥试验

探究不同植物残体还田条件下微生物关键种如何影响木质素酚的浓度(木质素酚与土壤有机碳的比值),旨在为不同有机物料还田培肥土壤提供理论和技术依据。本研究以河西绿洲灌区的灌漠土作为研究对象,开展了30 a以施加绿肥(GM)、小麦秸秆(SW)、氮肥(N)、绿肥配施氮肥(GMN)、小麦秸秆配施氮肥(SWN)以及不施肥(CK) 6种不同施肥处理的培肥试验。结果表明:GM和SW处理的土壤有机碳含量显著高于其他处理;有小麦秸秆参与还田的处理显著提高了总木质素酚浓度以及3种木质素酚类单体的浓度,其中总木质素酚浓度在SW处理中分别比CK、GM、N、GMN和SWN处理高了109%、122%、115%、164%和57%;对比不施肥和施化肥处理,植物残体还田显著提高了微生物关键种F3(盘菌纲,Pezizomycetes)、F26(被孢霉菌纲,Mortierellomycetes)、F173(粪壳菌纲,Sordariomycetes)、B74(阿尔法变形菌纲,Alphaproteobacteria)和B87(放线菌纲,Actinobacteria)的相对丰度。本研究共鉴定出15个关键种,其中关键种B831(属阿尔法变形菌纲)与木质素酚浓度呈显著的正相关关系,并且在SW处理下显著富集。本研究为农业生态系统不同培肥方式下微生物关键种如何影响植物衍生的木质素酚提供了科学参考,为深入了解植物残体还田对土壤有机碳周转的影响提供了理论依据。

金属氧化物负载钌催化木质素衍生酚类化合物制备环己醇的研究

本研究采用初湿浸渍法,制备得到一系列钌负载于金属氧化物载体的催化剂(Ru/CeO_(2)、Ru/Nb_(2)O_(5)、Ru/ZrO_(2)、Ru/Al_(2)O_(3)和Ru/CeOx),用于木质素衍生酚类化合物苯酚提质加氢转化为环己醇的研究。通过采用X射线晶体衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等手段对所制备催化剂进行结构和物化特征的表征,发现Ru/CeOx中含有的氧空位可以很好地吸附带有含氧基团的原料,从而有利于苯酚的高效加氢;同时XPS表明,Ru/CeOx中的有效活性中心RuO_(2)和Ru0是催化加氢的活性位点,因此,氧空位和金属活性位点的共同作用使得催化剂有较好的加氢活性。探究了反应温度、压力、时间对加氢效果的影响,发现催化剂能够在140℃下使苯酚完全转化,得到目标产物环己醇得率为90.2%,并对催化剂的循环特性进行考察,发现循环使用四次后催化剂仍表现出优异的加氢活性。同时采用GC-MS检测加氢过程的中间产物,进而推断出苯酚加氢过程的反应路径。

盐肤木叶中化学成分及抗氧化活性研究

研究盐肤木Rhus chinensis Mill.叶的化学成分。利用硅胶柱色谱、Sephadex LH-20柱色谱和半制备高效液相色谱等技术,从盐肤木叶95%乙醇提取物中分离纯化得到了15个化合物。根据化合物的理化性质和波谱数据确定了它们的结构,分别为3-hydroxy-5-methylphenol 1-O-β-D-(6′-benzoyl)glucopyranoside(1)、对羟基苯乙醇(2)、松脂素(3)、(3 S,5 R,6 S,7 E)-3,5,6-trihydroxy-7-megastigmen-9-one(4)、丁香脂素(5)、2,4,6-三羟基苯乙酮(6)、野漆树双黄酮(7)、去氢吐叶醇(8)、槲皮素(9)、没食子酸乙酯(10)、7 S,8 R-二氢去氢双松柏醇(11)、贝壳杉黄酮(12)、4,6-二羟基-2-O-(β-D-吡喃葡萄糖苷)苯乙酮(13)、3-hydroxy-5-methylphenol 1-O-β-D-(6′-galloyl)glucopyranoside(14)、debiloside A(15)。其中化合物1为新化合物,化合物2、4、6、7、8、13、15为首次从盐肤木属中分离得到。DPPH、ABTS自由基清除实验结果显示,化合物9、10、11、14对DPPH、ABTS自由基均表现出良好的清除活性,其中化合物9和10活性最为显著,强于阳性对照V C。

圆竹酚醛树脂复合管材的制备及其性能

在竹材工业化利用中,多将竹材分解为小单元竹篾或将竹材展平后进行加工,同时对竹材复合材料的实验室研究多以竹纤维和小尺寸竹片为主,直接利用圆竹本身结构特性制备管材的应用案例较少。以圆竹为对象,制备圆竹酚醛树脂复合管材,充分利用其中空的结构特性,以期为“以竹代木”“以竹代塑”提供一种新的途径。首先通过对圆竹进行脱木素提高其渗透性;随后真空浸渍酚醛树脂,并在自制模具中进行环形加压固化,验证了圆竹酚醛树脂浸渍复合工艺方法的可行性;同时研究了不同压力条件下成型的圆竹酚醛树脂复合管材的尺寸稳定性、润湿性以及微观结构变化。通过压缩率测试、剖面密度测试以及电镜观察发现,圆竹酚醛树脂复合管材径向上存在差异,两端面压缩密实化程度较高,中心层则较低。内外端面的竹材细胞细胞壁塌陷,与酚醛树脂形成致密结构,中心层的竹材细胞微观结构变化较小。经过处理的圆竹在环形加压固化成型后具有较高的压缩率和较低的径向吸湿回复率,圆竹酚醛树脂复合管材的尺寸稳定性相比于未处理圆竹有较大提升,同时,复合管材的吸水性能、润湿性能都较未处理圆竹明显下降。

木质素衍生酚类化合物催化加氢脱氧制备液体燃料研究进展

生物质中的木质素衍生酚类化合物具有含氧量高、稳定性差等缺点,通过加氢脱氧反应提质可以制备高品质生物液体燃料,对双碳目标的实现有重要的现实意义。综述了近年来用于木质素衍生酚类化合物反应的金属负载型催化剂,首先从单金属和双金属组分的角度分析金属间协同效应对加氢脱氧反应性能的影响。然后,针对金属位点特性对加氢脱氧反应的影响,讨论金属粒度、金属分散度和单原子金属催化剂的催化活性,阐明金属位点特性的影响因素,及其对加氢脱氧反应机理的影响机制。随后,基于载体对金属位点的影响,探讨载体特性与金属位点特性的关联因素,揭示载体对金属活性位点的影响机制。最后,对金属负载型催化剂的发展方向进行展望。

Interception, degradation and contributions of terrestrial organic carbon obtained from lignin analysis in Wujiang River, southwest China

Understanding the fate of terrestrial organic carbon(OC)in a cascade impoundment system is critical for recognizing the role of carbon sink for reservoirs.Surface sediments collected from eight cascade reservoirs across the Wujiang River,southwestern China,were analyzed for elemental and stable carbon isotopic(δ^13C)composition,and lignin phenols(∑8 andΛ8)to investigate the spatial distribution,contribution,origin and degradation of sedimentary terrestrial OC.The values of total organic carbon(TOC)and∑8 exhibited a remarkable reduction along the upstream-downstream transect suggesting the trapping effect of cascade-damming.A relatively broad range ofδ^13C(-26.61 to-25.54%,95%CI)and C/N(6.80-18.20)indicated mixed allochthonous/autochthonous OC sources in surface sediments.The quantitative simulation indicates that the OC of the sediments mainly was derived from terrestrial organic matter.Soilderived OC rather than C_(3)vascular plant-derived OC makes a major contribution to sedimentary terrestrial OC in reservoirs on karst terrain.As evidenced by lignin compositions andδ^13C,the predominant vascular plant origins of terrestrial OC along the Wujiang River are non-woody angiosperm C_(3)plants.The aged reservoirs showed a trend of increasing contribution of autochthonous OC,which potentially weaken the role of carbon sink for reservoirs.The relationship between runoff inputs,watershed area/water surface area ratios,and water residence time and Λ8 were explored,indicating the natural and anthropogenic influences on terrestrial OC remains very complex in a cascade-damming river.

高反应性木质素的高效提取及其制备生物聚氨酯泡沫

为了解决木质素参与聚氨酯泡沫反应存在结构复杂、纯度低、分子质量大、反应性较低等问题,本研究以天然竹粉为原料,利用氯化胆碱(ChCl)和草酸六水合物(Oad)制备低共熔溶剂(DES)作为提取溶剂,结合超声波辅助技术提取高活性酚羟基木质素,并将其作为反应单体替代部分石化多元醇,通过全水发泡法制备木质素聚氨酯泡沫(LPUF),并对其化学结构、微观形貌和力学性能进行分析。研究结果表明:基于DES超声波辅助处理未破坏木质素的基本结构,LPUF成功制备;较优的提取工艺条件为提取温度80℃、超声波作用时间0.5 h、超声波功率70 W,此条件下木质素含酚羟基8.8%、提取率高达87.8%。当木质素与聚乙二醇200(PEG-200),聚乙二醇400(PEG-400)和六亚甲基二异氰酸酯(HDI)的质量比为1∶84∶23∶155,所制备的木质素聚氨酯泡沫LPUF-2,平均孔径261.66μm,弹性模量3 MPa,经1000次压缩循环,LPUF-2最大应力为22.26 kPa,仍能保持初始应力的84%以上,显示出优异的力学性能及稳定性。

木质素基酚醛树脂的制备和过程优化

生物炼制工业中得到的酶解木质素较好地保留了原有木质素的结构特性,具有丰富的醇羟基和酚羟基等活性基团,可应用于生物基酚醛树脂的制备。本文对酶解木质素进行纯度、醇羟基和酚羟基结构表征,并替代部分苯酚用于酚醛树脂(PF)的合成及应用性能的研究。受限于木质素结构的复杂程度,无法有效确定反应进程并优化,提出通过在线红外光谱仪实时记录关键峰变化来实现跟踪木质素基酚醛树脂的制备过程。以1020cm^(-1)附近红外吸收峰研究体系中甲醛量的变化规律,优化木质素酚醛树脂工艺条件。结果表明,采用多步反应形式添加甲醛和氢氧化钠控制反应体系pH大于10.5,有利于酚醛树脂的合成;制备过程中理想聚合温度控制在88~95℃,木质素添加量最大可达到60%,制得酚醛树脂胶黏剂用于胶合板制备,胶合强度达到0.90MPa,甲醛释放量低至0.142mg/L,均满足E0级Ⅰ类胶合板要求。

碳纤维增强木质素基酚醛树脂复合材料的制备及其性能

采用碱催化酚化的方式增加木质素反应活性以替代苯酚,用于制备酚醛树脂及碳纤维增强木质素基酚醛树脂复合材料,探讨了碱催化酚化工艺条件对木质素结构的影响,表征了不同取代比的木质素基酚醛树脂的结构,以及碳纤维增强木质素基酚醛树脂复合材料的形貌和力学性能。结果表明:经碱催化酚化的木质素反应活性明显增加,最佳工艺条件为温度90℃,时间90 min,碱用量4%(w);木质素基酚醛树脂与传统酚醛树脂结构相似,当木质素替代率为30%(w)时,可获得弯曲性能和层间剪切强度高的碳纤维增强木质素基酚醛树脂复合材料。

蔗渣木质素液化影响因素及其产物表征

生物质液化是实现农林废弃物的高值转化和梯次化替代化工原料的重要技术手段。本文选用有机溶剂液化法对蔗渣木质素进行液化,探究不同液化参数(催化剂量,液固比,液化温度,液化时间)对其液化效率的影响,并结合正交试验进行液化工艺优化,同时对液化产物进行表征。结果表明:蔗渣木质素液化优化工艺参数为:液化温度150℃,液化时间1 h,液固比3∶1,催化剂量15%,此时残渣率为0.87%。蔗渣木质素在苯酚和硫酸的共同作用下,由原本的球形、球凹形结构降解成残渣颗粒。液化反应通过裂解、脱水、脱氢、脱氧和脱羧等方式,断裂连接蔗渣木质素大分子结构间的醚键和碳碳键,并通过缩合、羟甲基化和醚化反应重新排列液化中间产物中的小分子片段,最终形成较稳定的、可溶于苯酚的复杂混合物。

Soybean Seed Phenolics, Sugars, and Minerals Are Altered by Charcoal Rot Infection in MG III Soybean Cultivars

Soybean seed is a major source of phytochemical compounds that impact human health nutrition and livestock meal. Charcoal rot is a disease caused by the fungus Macrophomina phaseolina (Tassi) Goid, and thought to infect the plants through roots by a toxin-mediated mechanism, resulting in yield loss and poor seed quality, especially under drought conditions. Limited information is available on the effect of charcoal rot on seed phytochemical compounds and mineral nutrition in soybean. Therefore, the objective of this research was to investigate the effect of charcoal rot infection on seed phenol, seed coat lignin, isoflavones, and minerals using susceptible (S) (DK 3964) and moderately resistant (MR) (AG 3905) maturity group (MG)III soybean cultivars to charcoal rot. A two-year field experiment was conducted, and infested soil with charcoal rot (infested soil conditions, INF) or control (non-infested soil conditions, NINF) was used. The results showed that the moderately resistant genotype had higher concentrations of seed phenolics, total isoflavones, and seed coat lignin under infested and non-infested conditions and under irrigated or non-irrigated conditions compared with the susceptible genotype. The same general trend was found for seed K, Ca, P, Mn, Zn, B, and Cu concentrations in the moderately resistant genotype compared with the susceptible genotype. Our research demonstrated that these seed phytochemical constituents may explain the differences between susceptible and moderately resistant cultivars and may play an important role in the resistance to charcoal rot.

Effect of shade stress on lignin biosynthesis in soybean stems

To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12（shade tolerant） and Nan 032-4（shade susceptible） grew under normal light and shade conditions（the photosynthetically active radiation and the ratio of red：far-red were lower than normal light condition）. Lignin accumulation, transcripts of genes involved in lignin biosynthesis, and intermediates content of lignin biosynthesis were analyzed. Both soybean varieties suffered shade stress had increased plant heights and internode lengths, and reduced stem diameters and lignin accumulation in stems. The expression levels of lignin-related genes were significantly influenced by shade stress, with interactions between the light environment and variety. The gene of 3-hydroxylase（C3H）, cinnamoyl-Co A reductase（CCR）, caffeoylCoAO-methyltransferase（CCoAOMT）, and peroxidase（POD） attributed to lignin biosynthesis under shade stress, and the down-regulation of these genes resulted in lower caffeic, sinapic, and ferulic acid levels, which caused a further decrease in lignin biosynthesis. Under shade stress, the shade tolerant soybean variety（Nandou 12） showed stiffer stems, higher lignin content, and greater gene expression level and higher metabolite contents than shade susceptible one. So these characteristics could be used for screening the shade-tolerant soybean for intercropping.